Hello Mark, good to see you here :)

I am trying to model it in NonSeq mode, because it is part of an instrument and I would need to simulate the signal in the detector. 

So far I have put two rectangular volumes to create the cavity and played around with the coatings for Front/Rear faces but the result is that all wavelengths get through. So the physics of resonance is not happening. Im doing something wrong

Any tips ?

thx in advance

Dear Sandrine, 

thanks a lot for your input. Getting those rings in NonSeq is something !!

I have been checking your file and I have the following comments:

- It is weird that the results do no react when I modify the coatings from 'FP' to any other.

- The same happens when I change the wavelength or other parameters of the system.

So in general it doesnot react to any change. As you know, a Fabry-Perot filters wavelength by fine-tuning the distance between mirrors, and in the zemax sample files the distance between the two plates is zero. that is the point I dont see. Ideally , I would like to simulate in OS something like this web simulator:

https://lightmachinery.com/optical-design-center/etalon-designer/

Should I open a case or shall we follow here?

Thanks,

Javier

Hello Mark,

thanks for the reply. I have been looking into it and I have the following comments:

- indeed it reacts to changes in the primary wavelength. Still havent changed the thickness of Air

- the Transmission vs Wavelength is flat to 1 in the NonSeq model, I dont know the reason

- In your FP 'sandwhich', ALUM is defined before as a material (MATE) with = 0.55  0.7  -7.0  . So my next question is, where is the reflectivity of this aluminum defined?. The reflectivy defines then the Finesse and in general the performance of the FabryPerot experiment

Thanks a lot 

Hi Javier

I have updated the non-sequential file:

• In the Transmission vs Wavelength, I have modified the settings to plot the front face of the 3rd object (check the settings). 


• I have changed the paraxial lens by a real lens.

Sandrine

Hello Sandrine and Mark,

I start to believe that my issues are more related to the Detector Viewers than the FP itself,, which is already tricky. Here I drop some comments:

- The default sandwich of coatings in None-FP-FP-None. I have noticed that if I remove one FP it behaves different:

None-FP-None-None (ie, modify surface 3, Front) gives a (more or less gaussian) spot of light, with no interference at all. Whereas...

None-None-FP-None (ie, modify surface 2, Back) gives rings so interference is happening.

Does it mean that I dont need to apply the coating on both , and only the Front side of the second mirror is enough ?

- There must be something that stays in memory so that Detector Viewers show incorrect signal. If I try to recover the default rings at 0,55 um , it shows something different. The same happens when I change to different wavelengths.

Even if I reopen the file, it opens several Viewers that I did close (and did not save) before !. The only way is to shut down OS and launch it again.

Sandrine, I still haven't looked at your file with a real lens. I will give you feedback asap

Thanks a lot,

JMV 

Thanks for thereply Sandrine. Clearly the 'nesting rule' applies there.

Im still fighting to get my etalon , in my caso made of HfO2 and SiO2 for the UV. Seems to be quite standard mix for the UV. I will keep you posted

thanks,

JMV

Hello Mark and Sandrine,

I am in the process of modeling a FP etalon system and I have used both sequential and non-sequential modes implementing the etalon as a coating based on the zemax example file and as described above  The results for this idealized case seem reasonable.

A useful simulation tool for my problem would be an opto-mechanical model where I can see the effect of tilt and stress on the etalon plates.  I have tried to follow the approach above from Javier using an 80% reflective coating on each of the air spaced etalon plates but this does not seem to be working.  Perhaps it is just not possible to trace enough rays.  If this approach did work, I could tilt one of the plates , add curvature or a TIRR or Zernike sag surface to represent deformation to study these effects and develop an error budget for my system.

In the past, I have used Solidworks simulation and Sigfit to combine opto-mechanical effects from FEA results into my Zemax model.   Are there any tricks you can recommend to develop an etalon model that would lend itself to this type of analysis?  Can tilt or irregularity be introduced in the coating to simulate these effects?

Thanks,

Pat

Thanks Mark.  I will investigate tapered coatings.  I have no experience in this area, so hopefully I can figure it out from your examples.

Regards,

Pat